Couplers of this general nature are well known for use in subsea equipment, particularly associated with subsea wellheads, and are normally used to allow connection of highly pressurized hydraulic fluid. Very typically there is provided a ‘stab plate’ on which an array of couplers is mounted and which can provide simultaneous connection of a multiplicity of coupling pairs.
Couplers of this general nature usually have self-sealing valves which are usually constituted by spring-loaded poppet valves, one in each coupler, and are arranged so that when the couplers are mated the valve poppets are lifted from their respective seats to provide fluid connection between the couplers. However, the invention is not limited to this form of connection.
It is usually necessary to provide a seal between the probe of the male coupler and its receiving socket. For convenience such a seal is disposed, usually in an internal annular recess, in the body of the female coupler and normally this seal provides a radial seal between the socket and the probe. For preference, this (primary) seal provides a metal-to-metal sealing between the couplers and although several different forms of seal have been proposed, one preferred form is a metal seal in the form of a hollow ring which can provide radial sealing between the couplers. For preference there is more than one seal and it is known to provide a secondary, polymeric, hollow annular seal spaced apart from the primary seal and likewise providing radial sealing between the couplers.
It is necessary to provide a means of retaining at least the primary seal and preferably also the secondary seal within the female coupler. The main object of the invention is to provide an improved retainer of simple and reliable construction, which can provide a direct seal with the female coupler so as to provide sealing between the region of the primary seal that it retains and the exterior of the coupler. One purpose of such a seal is the prevention of leakage from the coupler should the primary seal be displaced or otherwise fail.
Three examples of the state of the art are the documents U.S. Pat. No. 4,834,139-A, GB-2407628-A and GB-2394994-A.
In the coupling described in U.S. Pat. No. 4,834,139-A, the metal C-seal is disposed in an annular shoulder at the rim of the socket and is retained by means of an external sleeve which also has an internal annular groove that accommodates an elastomeric O-ring constituting a second radial seal between the couplers. In the coupling described in GB-2407628-A, the C-seal is loosely disposed in a shoulder at the end of a seal carrier, which has an annular groove outwardly spaced form the shoulder and accommodating an O-ring which makes an axial seal with the body of the coupler. This groove is formed in an annular ridge with sloping sides engaging a complementary groove in the coupler. The carrier also carries an elastomeric crown seal and is retained in the socket by another threaded sleeve. In the coupling described in GB-2394994-A, the C-seal is loosely positioned in an annular shoulder at the end of an internal seal carrier which has a conical recess abutting a conical protrusion surrounding the socket in the female coupler. A separate threaded sleeve is required to retain the seal carrier in position.